CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen Future electron-proton and electron-nucleus colliders, eRHIC and LHeC Joakim Nystrand University of Bergen The road to the future …

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen The Physics of Deep Inelastic e-p Scattering Photon-induced interactions probe the partonic structure of nucleons/nuclei, F 2 (x,Q 2 ). These measurements are necessary as reference for pp collisions at the LHC. Achievement of HERA

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen What’s the problem with Heavy-Ion Collisions?  We don’t know what we are colliding! At RHIC and even more so at LHC, the partonic interactions dominate (or at least these are the interactions we are most interested in). Yet, very little is known about the nuclear parton distributions There is the EMC effect, there is anti-shadowing, and there is shadowing. But the details below <10 -2 are unknown.

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen Eskola, Paukkunen, Salgado arXiv: Uncertainty in the gluon distribution for a heavy nucleus (Pb) (Q 2  2 GeV 2 ):

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen What’s the remedy for this?  Redo the HERA exercise: Build an electron+Ion Collider! There are several ideas for this: A GeV at BNL GeV at JLab GeV at CERN HERA: GeV See article by Max Klein in latest Cern Courier (April 2009)

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen Center-of-mass Energy vs. Luminosity Note: eRHIC would run also w/ polarized protons; LHeC will extend the energy range from HERA in e+p.

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen eRHIC Design Concepts (D. Lowenstein QM2006) simpler IR design multiple IRs possible E e ~ 20 GeV possible luminosity Linac-Ring design Ring-Ring design simpler ring design one IR possible less R&D effort luminosity 2 designs are under consideration

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen RHIC II

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen Similar Design Concepts for LHeC Linac-Ring design Ring-Ring design

CERN Evaluation Meeting, Bergen, April 2009Joakim Nystrand, University of Bergen eRHIC Detector(s) Studying e+A or e+p collisions will require a new, dedicated detector. - Asymmetric event topologies very different from symmetric pp or AA. - Wide coverage for electron id. (calorimeters) - Zeus/H1 covers 3° <  < 175°  |  | < 3 - Desirable to extend this to |  | < 4 (low x, Q 2 ) - Otherwise a “standard high-energy physics detector”.

2020 is far away… In the meantime, we will have to do with ultra- peripheral collisions, i.e. use the EM field of the protons and ions at hadron colliders. CDF Collaboration, arXiv: PHENIX Collaboration, arXiv: See e.g. recent results from CDF and PHENIX, p+p  p+p+J/ , Au+Au  Au+Au+J/ 